Pressure pain thresholds in normal muscles: reliability, measurement effects, and topographic differences

Area of Science:

• Biomedical Engineering
• Musculoskeletal Research
• Pain Measurement

Background:

• Pressure pain thresholds (PPT) are used to assess muscle tenderness.
• Understanding variability in PPT measurements is crucial for accurate clinical assessment.
• The masseter and temporalis muscles are key masticatory muscles often examined for tenderness.

Purpose of the Study:

• To determine measurement effects, topographic variability, and reliability of PPT in the masseter and temporalis muscles.
• To establish PPT as a reliable index of normal tenderness in these muscles.
• To identify factors influencing PPT measurement variability.

Main Methods:

• Utilized the ascending method of limits to measure PPT in 10 healthy subjects.
• Conducted experiments measuring PPT across multiple trials, sites, and sessions.
• Employed repeated measures analysis of variance to interpret the data.

Main Results:

• PPT was significantly higher in the temporalis muscle compared to the masseter muscle.
• PPT was significantly higher at tendon areas than at muscle belly areas.
• No significant measurement effects were found across 5 trials; averaging the first two trials improved PPT estimation.

Conclusions:

• Topographic differences in PPT exist between the temporalis and masseter muscles, and between tendon and belly areas.
• Averaging the first two PPT measurements enhances reliability and reduces variability.
• Between-session PPT measurements demonstrated high reliability, supporting its use in longitudinal studies.